The present invention relates to an image processing apparatus and method and, in particular, to an image processing apparatus and method which classify an image as one of several classes in accordance with its property and subject it to a process corresponding to its class.
For example, among various methods for performing image processing such as converting a standard or low resolution image (hereinafter referred to as an SD image where appropriate) into a high resolution image (hereinafter referred to as an HD image where appropriate) is a method which classifies each block that constitutes an SD image as one of predetermined classes in accordance with its property and subjects it to image processing corresponding to its class.
For example, it is now assumed that, as shown in FIG. 1A, a block of 2.times.2 pixels is formed by a certain subject pixel and three pixels adjacent to it and each pixel is expressed by one bit (that is, it has a level of 0 or 1). In this case, as shown in FIG. 1B, blocks of 4 (2.times.2) pixels can be classified into 16 (=(2.sup.1).sup.4) patterns based on the distribution of the levels of the respective pixels. The classification means this type of division into patterns, and the classification enables each block to be subjected to image processing suitable for its class, i.e., its image property.
However, image properties (features) are not represented by only the level distribution of pixels. It would therefore be considered that an image may be processed more properly by classifying it by using some other feature quantity.